Greenstone apparently was trying to do exactly that during Saturday's home game against Southeast Missouri State when Tennessee State defensive end Latrelle Lee punched him twice in the side of the head, sending him to the ground.
Tennessee State responded quickly, with head coach Rod Reed kicking Lee off the team and the university dismissing him outright Monday.
Greenstone, a defensive tackle at Vanderbilt from 2007-11, was named TSU's strength and conditioning coach in 2016 and serves as the "get back" coach for the sideline.
The school, which would not even confirm the name of the student involved in the sideline incident, has not officially announced that Lee has been expelled.
According to The Tennessean, Greenstone's job is to keep players away from the sideline to avoid getting penalized. "We are committed to supporting the coach who was personally affected and our concern now is with him".
TSU (6-4, 2-4 in the OVC) won the game, played on campus at Hale Stadium, 23-20. There is no word yet as to why in the hell Lee chose to poach Greenstone.
Lee played in a total of 16 games during his freshman and sophomore seasons, but started just two game this season.